Great (large) Toe Prosthesis And Method Of Implanting - Patent 4156296 by Patents-185

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									United States Patent [19]
4,156,296
[45] May 29,1979
[ii]
Johnson et ah
[54] GREAT (LARGE) TOE PROSTHESIS AND
METHOD OF IMPLANTING
thritic or Destroyed Joints in the Hand", by A. B.
Swanson, Surgical Clinics of North America, vol. 48,
No. 5, Oct. 1968, pp. 1119-1122.
[75] Inventors: Kenneth A. Johnson, Rochester,
Minn.; Allan Vegell, Warsaw, Ind.
Primary Examiner—Ronald L. Frinks
Attorney, Agent, or Firm—Woodard, Weikart, Emhardt
& Naughton
[73] Assignee: Bio-Dynamics, Inc., Indianapolis,
Ind.
[21]	Appl. No.: 785,942
[22]	Filed:
[51]	Int.CI.2
[52]	U.S.CL
[58] Field of Search
[57]
ABSTRACT
Apr. 8, 1977
An endoprosthetic device for a prosthesis between met¬
atarsal and phalangeal bones comprising proximal and
distal components which are engageable with each
other. The proximal component has a convex, part-
spherical bearing surface and a stem projecting from
this surface for securing the proximal component into
the end of the first metatarsal. The distal component has
a concave, part-spherical bearing surface and a stem
projecting from this surface for securing the distal com¬
ponent into the end of the phalanx adjacent to the first
metatarsal. The engagement of the two components
forms a less-than-hemispherical articulation.
	A61F 1/24
3/1.91; 128/92 C
	3/1.9-1.913;
128/92 C
References Cited
U.S. PATENT DOCUMENTS
3,506,982 4/1970	Steffee	
3,965,489	6/1976	Freeman et al	
3,975,778	8/1976	Newton 	
3,992,726 11/1976	Freeman et al	
4,024,588	5/1977	Janssen et al	
OTHER PUBLICATIONS
"Silicone Rubber Implants for Replacement of Ar-
[56]
3/1.91
3/1.91
3/1.91
3/1.91
3/1.91
6 Claims, 6 Drawing Figures
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U.S. Patent
4,156,296
May 29, 1979
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4,156,296
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bearing surface forms a less-than-hemispherical area of
contact wherein the engaging bearing surfaces are free
GREAT (LARGE) TOE PROSTHESIS AND
METHOD OF IMPLANTING
BACKGROUND OF THE INVENTION
to separate.
Another embodiment of the present invention might
5 include a method of implanting a prosthetic device
having mutually-engageable proximal and distal com¬
ponents for replacement of a metatarso-phalangeal joint
which comprises the following steps. First, making an
incision over the joint, removing a portion of bone from
Prosthetic devices for use as joints to replace defec- 10 the end of the metatarsal adjacent the joint and inserting
the proximal component into the metatarsal. Next, re¬
moving a portion of bone from the end of the proximal
plalanx adjacent the joint and inserting the distal com¬
ponent into the proximal phalanx. Finally, closing the
1. Field of the Invention
This invention relates in general to prosthetic devices
for the replacement of joints in human beings.
2. Description of the Prior Art
tive natural joints have been used by the medical profes¬
sion for several years. Typically, such devices consist of
two prosthetic members which are implanted into or
attached to the anatomy of the subject at the location of
the defective joint. The two members are constructed 15 incision,
and positioned such that as the muscles and tendons
exert a force on the contiguous natural bones, the move¬
ment of the prosthetic members with respect to each
other simulates that of the natural joint. Unfortunately,
many prostheses have been found to be impractical 20
because the assembly of the components to one another
after each component is implanted is difficult and often
requires special surgical tools..
One object of the present invention is to provide an
improved prosthetic joint design. Another object of the
present invention is to provide an improved method of
implanting a prosthesis.
Related objects and advantages of the present inven¬
tion will be apparent from the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary top view of a prosthetic
closes a prosthetic joint suitable for replacement of the 25 device according to the present invention,
metacarpophalangeal and the interphalangeal joints of
the hand and for the knee. The device employs a socket
element and a ball element which engage one another
and the device is constructed to simulate the motion of
The device of Schultz, U.S. Pat. No. 3,760,427, dis-
FIG. 2 is a fragmentary side view of the FIG. 1 pros¬
thetic device.
FIG. 3 is a fragmentary top view of the FIG. 1 pros¬
thetic device as implanted into adjacent bones.
FIG. 4 is a fragmentary view of the device and bones
a bony condyle. Each element has an intramedullary 30
stem which is inserted into the medullary canal of a
bone. One disadvantage of this device is the surgical
difficulty of positioning the two elements relative to
each other so that they function properly.
of FIG. 3.
FIG. 5 is a perspective view of the metatarsal compo¬
nent of the FIG. 1 prosthetic device.
FIG. 6 is a perspective view of the phalanx compo-
The device of Steffee, U.S. Pat. No. 3,506,982, also 35 nent of the FIG. 1 prosthetic device,
discloses a two-member, ball and socket articulation
which incorporates a stem attached to each member for
securing each member in place. Each stem is surgically
inserted into intramedullary bone canals on each side of
DESCRIPTION OF THE PREFERRED
EMBODIMENT
For the purposes of promoting an understanding of
the joint being replaced such that the ball member is 40 the principles of the invention, reference will now be
engaged by the socket member.
The device of Devas, U.S. Pat. No. 3,651,521, dis¬
closes a prosthetic device which comprises mutually-
engageable male and female components and affords
pivotal rotation in a plane.
Each of these prior art devices involve a style of ball
and socket prosthetic joint with greater than 180° of
engagement. Each device also incorporates mechanical
limitations which reduce the degree of freedom of the
joint to that of a hinge-like movement. A disadvantage 50
of such hinge-type joints is that the flexion and exten¬
sion motion of the appendage may expose sharp edges
of the prosthetic device to the enclosing soft tissue and
thus such devices are painful to the subject with even
moderate use.
made to the embodiment illustrated in the drawings and
specific language will be used to describe the same. It
will nevertheless be understood that no limitation of the
scope of the invention is thereby intended, such alter-
45 ations and further modifications in the illustrated de¬
vice, and such further applications of the principles of
the invention as illustrated therein being contemplated
as would normally occur to one skilled in the art to
which the invention relates.
Referring to FIGS. 1 and 2, there is illustrated an
endoprosthetic device 10 comprising metatarsal compo¬
nent 11 and phalanx component 12. FIG. 1 is a top view
of device 10 and FIG. 2 is a side view of device 10. The
metatarsal component 11 has a convex, part-spherical
55 bearing surface 13 and a stem 16 of generally-rectangu¬
lar cross section projecting from the rear surface 17 of
the component. The rear surface 17 of bearing surface
13 is a concave, part-spherical surface. Stem 16 is posi¬
tioned approximately in the center of rear surface 17
SUMMARY OF THE INVENTION
One embodiment of the present invention is an endo¬
prosthetic device for the replacement of a joint in fin¬
gers and toes comprising mutually-engageable, proxi- 60 and is perpendicular to rear surface 17. In the preferred
mal and distal components. The proximal component
has a convex, part-spherical bearing surface and a stem
projecting from the rear of the proximal component for
affixing into a bone. The distal component has a con¬
cave, part-spherical bearing surface and a stem project- 65 means of the single-piece construction of component 11.
ing from the rear of the distal component for affixing
into a bone. The engagement of the convex, part-spheri¬
cal bearing surface with the concave, part-spherical
embodiment, stem 16 is an integral part of metatarsal
component 11. Although stem 16 could be attached to
rear surface 17 by means of a screw or bolt, or possibly
welded, greater component strength is provided by
The phalanx component 12 has a concave, part-
spherical bearing surface 18 and a stem 19 of generally-
rectangular cross section projecting from the rear sur-
4,156,296
3
4
face 22 of the component. The rear surface 22 of bear¬
ing surface 18 is a generally-flat surface, externally cir¬
cular in shape. Stem 19 is positioned in approximately
the center of rear surface 22 and is perpendicular to rear
surface 22. In the preferred embodiment, stem 19 is an 5 flexed, and with most natural toe motions the toe will be
intregal part of phalanx component 12 and affords the
same advantages of improved strength as described for
the metatarsal component 11.
The radius of convex bearing surface 13 of metatarsal
component 11 is the same dimension as the radius of 10 engagement the two components will remain in contact,
concave bearing surface 18 of phalanx component 12.
Consequently, the metatarsal component 11 and pha¬
lanx component 12 are capable of engagement with one
another at their bearing surfaces 13 and 18, respectively.
Sliding motion is permitted between surfaces 13 and 18 15 of sharp edges. Consequently, flexing the prosthetic
in virtually all directions similar to a ball and socket
connection.
the prosthetic joint. Surface of engagement 29 which is
a common interface for both bearing surfaces 13 and 18
is the surface where sliding motion occurs between the
two components 11 and 12, as the toe is moderately
only moderately flexed. However, it is possible for the
toe to be flexed to such a degree that on one side of
surface of engagement 29 the two components will
separate slightly. On the other side of the surface of
The metatarsal and phalanx bones are prepared in such
a way prior to anchoring the prosthetic components in
place that the contours of the exposed surfaces (of both
the bones and prosthesis) are generally smooth and free
joint will not be a painful movement.
As is illustrated in FIGS. 3 and 4, the engaging bear¬
ing surfaces 13 and 18 are free to slide relative to each
other in a universal, unrestrained manner in that there
FIGS. 3 and 4 show the metatarsal component 11 and
phalanx component 12 of endoprosthetic device 10 as
implanted into their corresponding bones on each side 20 are not stop surfaces present on or adjacent the bearing
of the first metatarso-phalangeal joint for which endo¬
prosthetic device 10 is a replacement. One feature of
device 10 is that the part-spherical bearing surface 13 of
the metatarsal component 11 has a surface area which is
noticeably larger than the surface area of the part- 25 tionship between convex bearing surface 13 and meta-
spherical bearing surface 18 of the phalanx component
12. This feature permits easy and comfortable articula¬
tion of the joint in that with normal flexing, the outer
edge of surface 18 of phalanx component 12 will remain
adjacent surface 13 and will not extend beyond the 30 to longitudinal axis line 26 is transverse axis line 27 and
outermost edge of surface 13 into the surrounding tissue
whereby such tissue might be pinched or irritated and
thereby cause discomfort. Bearing surface 13 also pro¬
vides a compatible surface against which the phalanx
component 12 may slide and the size of surface 13 pre- 35 equal to the maximum transverse dimension of the met-
cludes component 12 from contacting the natural bone
of the first metatarsal 24.
surfaces of either component. Any limitation to the
freedom of movement would thus be the result of the
tissue and ligaments surrounding the prosthetic joint. A
further feature of this prosthesis is the dimensional rela-
tarsal component 11. Longitudinal axis line 26 extends
through the approximate center of each component and
is substantially coincident with the longitudinal axes of
the bones (metatarsal 24 and phalanx 28). Perpendicular
consequently, any plane which is both parallel to line 27
and perpendicular to line 26 defines a suitable plane for
measuring a transverse dimension. As illustrated, the
maximum transverse dimension of bearing surface 13 is
atarsal component 11.
FIG. 5 is a perspective view of metatarsal component
11 showing the generally-rectangular cross section stem
16 in greater detail. Stem 16 has two planar surfaces 30
FIG. 3 is a skeletal representation of a top view and
FIG. 4 is a skeletal representation of a side view of a
human being's great (large) toe into which the device 10 40 and 31 longitudinally extending from rear surface 17 to
has been implanted. The generally-rectangular cross
section stem 16 of metatarsal component 11 is implanted
into distal end 23 of the human being's first metatarsal
24. The generally-rectangular cross section stem 19 of
phalanx component 12 is implanted into the proximal 45 Concave recesses 37 and 40 extend from surfaces 30 to
end 25 of the proximal phalanx 28 which is adjacent to
the first metatarsal 24. The length of stems 16 and 19
projecting from surfaces 17 and 22, respectively, must
be sufficient to allow each prosthetic component to be
rigidly anchored into the corresponding bone and such 50 showing the generally-rectangular cross section stem 19
stems may extend into the medullary canal of each
bone. Thus, in one example of the invention the length
of stem 16 is 0.28 inches and the length of stem 19 is 0.27
inches. Once the metatarsal component 11 and phalanx
component 12 are implanted in the first metatarsal 24 55 and 49, respectively, which are positioned approxi¬
mately half way between rear surface 22 and end 47.
Concave recesses 48 and 49 extend between surfaces 41
end 36 and sides 34 and 35 extending between surfaces
30 and 31. Sides 34 and 35 each have a concave recess
37 and 40, respectively, which are positioned approxi¬
mately half way between rear surface 17 and end 36.
surface 31 and serve to anchor metatarsal component 11
in place when implanted into the first metatarsal 24, as
shown in FIG. 4.
FIG. 6 is a perspective view of phalanx component 12
in greater detail. Stem 19 has two planar surfaces 41 and
42, longitudinally extending from rear surface 22 to end
47, and sides 43 and 46 extending between surfaces 41
and 42. Sides 43 and 46 each have a concave recess 48
and phalanx 28, respectively, their part-spherical bear¬
ing surfaces 13 and 18, respectively, are exposed and
adjacent to each other and engage one another.
Bearing surfaces 13 and 18 are designed to be less
than a hemisphere and will consequently form a les- 60 3.
s-than-hemispherical articulation wherein there is no
locking of one member to the other. There are no intri¬
cate features which interlock the metatarsal component
11 with the phalanx component 12 and bearing surfaces
13 and 18 of the two components are held together due 65 phalangeal joint is expressed of blood and is kept blood-
to the nature of the anatomy of the toe and the sur¬
rounding tissue. Similarly, proper joint alignment is
provided by the soft tissue of the toe which surrounds
and 42 and serve to anchor phalanx component 12 in
place when implanted into phalanx 28, as shown in FIG.
The implant procedure for endoprosthetic device 10
is done in an operating room with suitable operating
room sterility precautions. First, the foot is sterilely
prepared and the area surrounding the metatarso-
free by means of a tourniquet. Next a dorsomedial inci¬
sion is made over the metatarso-phalangeal joint and the
joint capsule is opened. Depending upon the pathologic
4,156,296
5
6
reason for the prosthetic insertion, the soft tissue about
the joint is manipulated in such a way as to achieve the
best result. Before prosthetic device 10 can be inserted,
a portion of bone must first be removed from the distal
end 23 of first metatarsal 24 (see FIGS. 3 and 4). As 5 other in a universal manner and being free of any stop
metatarsal component 11 is inserted, rear surface 17 will
come to rest on the distal end 23 and then metatarsal
component 11 is fixed to the first metatarsal 24 by the
use of a suitable polymerizing grouting material such as
methyl methacrylate. This material fills the various 10
voids which might be present between the bone and the
component stem and then the material hardens to rig¬
idly bond the component in place. The next step is to
remove the base of the proximal phalanx 28 at end 25
with a power-driven saw. Then after burr molding of 15
the area, phalanx component 12 is inserted until rear
surface 22 comes to rest on end 25. Phalanx component
12 is then fixed to phalanx 28 by the use of a suitable
polymerizing grouting material such as methyl methac¬
rylate. Finally, the soft tissue of the toe is closed around 20
both components 11,12 of prosthetic device 10 in such
a way as to give proper realignment of the prosthesis.
The preferred material for metatarsal component 11
is a substantially, physiologically inert metal such as
orthochrome and the preferred material for phalanx 25
component 12, polyethylene.
While the invention has been illustrated and de¬
scribed in detail in the drawings and foregoing descrip¬
tion, the same is to be considered as illustrative and not
restrictive in character, it being understood that only 30
the preferred embodiment has been shown and de¬
scribed and that all changes and modifications that
come within the spirit of the invention are desired to be
protected.
What is claimed is:
1. An endoprosthetic device for replacement of a
joint in fingers and toes which comprises only two
components, said two components being mutually en-
gageable and including a proximal component and a
distal component, the proximal component having a 40
convex, part-spherical bearing surface and a first stem
projecting from the rear of said proximal component for
affixing into a bone, the maximum transverse dimension
of said convex bearing surface equaling the maximum
transverse dimension of said proximal component, the 45
distal component having a concave, part-spherical bear¬
ing surface and a second stem projecting from the rear
of said distal component for affixing into a bone, said
convex, part-spherical bearing surface having a surface
the convex, part-spherical bearing surface with the
concave, part-spherical bearing surface forming a less-
than-hemispherical area of contact, said engaging
bearing surfaces being free to slide relative to each
surfaces.
2.	The endoprosthetic device of claim 1 in which
each stem has a pair of concave recesses in spaced-apart
relationship.
3.	The endoprosthetic device of claim 2 in which the
proximal components is made of a substantially, physio¬
logically inert metal and the distal component is made
of polyethylene.
4.	The endoprosthetic device of claim 3 in which the
proximal and distal components are of a size suitable for
a prosthesis of the metatarso-phalangeal joint of the first
metatarsal.
5.	A method of implanting a prosthetic device having
only two components, a proximal component and a
distal component, into a metatarsal and a proximal pha¬
lanx for replacement of a metatarso-phalangeal joint
which comprises the steps of:
making a dorsomedial incision over the metatarso¬
phalangeal joint;
removing a portion of bone from the end of the meta¬
tarsal adjacent said joint;
inserting the proximal component into the metatarsal
at said end, said proximal component having a
convex, part-spherical bearing surface, the maxi¬
mum transverse dimension of said convex, part-
spherical bearing surface equaling the maximum
transverse dimension of said proximal component;
removing a portion of bone from the end of the proxi¬
mal phalanx adjacent said joint;
inserting the distal component into the proximal pha¬
lanx at said end, said distal component having a
concave, part-spherical bearing surface with a sur¬
face area noticeably smaller than the surface area
of the convex, part-spherical bearing surface of the
proximal component, the engagement of said bear¬
ing surfaces forming a less-than-hemispherical area
of contact, said engaging bearing surfaces being
free to slide relative to each other in a universal
manner and being free of any stop surfaces; and
closing the incision.
6.	The method of implanting a prosthetic device as
recited in claim 5 comprising the additional steps of
affixing each component into the bone by means of a
35
area noticeably larger than the surface area of said con- 50 grouting compound subsequent to each inserting step,
cave, part-spherical bearing surface, the engagement of	♦ * ♦ ♦ ♦
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